Carb questions 05 to 06

[Dustin_Drews]

I am wondering why do thy swap the 05 carbs out for the 06 FRC carb when the 05 is 42mm and the 06 is 40mm?
Can someone please explain in detail? I could not locate anything in a search!
God Bless
Dustin Drews

[curryd]

Carbs from 05 and 06 are completely different. The 06 and up FCR carb is what everyone runs on their bikes and quads until fuel injection came about. It seems to be the carb everyone wanted. For size difference, not sure but that is what they came in. FCR carb is easier to change around and gives more performance. I have a 04 with the stock carb, and I think it runs good. I couldn't justify spending $300 or more for a carb unless you have to have the best for everything. I used a Dynojet jet kit for the 04.

[Ruf Racing]

This is usually done when modifying the 04/05 engines. Also they bore the FCR larger, (42 or 43.5) The throttle responds is superior to the old round slide. I run a 43.5 bored FCR on a 501 build, it was a big improvement. Well worth the coin! :macho

[Latemodel32]

If you swap a 05 to 06 fcr carb and its not bored or no motor mods you wont feel much diff at all just alittle quicker throttle reponse. You get the carb bored and have motor mods thats a diff ball game

[mx Eli]

the 04/05 is a 39mm and the 06+ fcr is a 42mm

[Ruf Racing]

Originally posted by mx Eli
the 04/05 is a 39mm and the 06+ fcr is a 42mm

Wrong! (04/05) 42mm round slide. 06 (40mm FCR).

[mx Eli]

really???:huh :huh :huh :huh :huh

well sorry for the missinformation

[Ruf Racing]

Originally posted by mx Eli

well sorry for the missinformation

No problem. Correct information is crucial. ;)

[d3ktrix]

Originally posted by Latemodel32
If you swap a 05 to 06 fcr carb and its not bored or no motor mods you wont feel much diff at all just alittle quicker throttle reponse. You get the carb bored and have motor mods thats a diff ball game

I had a stock bore FCR on a mostly stock 05 TRX.
While everyone pretty much agrees there is no peak HP gain, that little bit of throttle response change is quite drastic.
It'll change that slow roll on type of power that the 05 is know for into a snappy/accurate arm tugging power.
The bike will still feel the same in the higher gears because like stated, it doesn't add any HP. But when u are stabbing the throttle coming out of corners in the lower gears, you will notice a big difference.
If it is tuned right of course, if not all u will get is a lean bog :P

My opinion anyway.

[D Bergstrom]

Originally posted by d3ktrix
I had a stock bore FCR on a mostly stock 05 TRX.
While everyone pretty much agrees there is no peak HP gain, that little bit of throttle response change is quite drastic.
It'll change that slow roll on type of power that the 05 is know for into a snappy/accurate arm tugging power.
The bike will still feel the same in the higher gears because like stated, it doesn't add any HP. But when u are stabbing the throttle coming out of corners in the lower gears, you will notice a big difference.
If it is tuned right of course, if not all u will get is a lean bog :P

My opinion anyway.

I agree. The FCR carbs were one of the best mods I did to my 2004 and 2005 450R’s. I wish I would have done it sooner. It is not a little difference in throttle response, it was a HUGE difference.

When I bought my first FCR and installed it on my race quad, rode it a few times, then rode my other 450R with the stock carb and was amazed at the difference the FCR carb made. As soon as I got home from that ride, I found another FCR carb for that 450R also. I didn’t even want to ride the 450R with the stock carb any more! Both my FCR’s are unmodified also.

Just because a carb is bigger, doesn’t mean it is better. I know I have read that the stock 04/05 carb measures 42mm at the airbox side, but is only 39 or so at the head side. Never confirmed this, but I have read it more then once. I also not sure on the TRX FCR’s, but the CRF FCR’s, 07 and later are 41 mm, while previous years are 40 mm. Other then the FCR being a flat side and the stock carb being a round slide, I have no idea in the differences. I just know the FCR carb is well worth the money, at least for the riding I do.

Doug

[Lquad71]

What do u need to do the mod?
I dont want to get the adapter..im wondering if i can get an 06+ air boot and airbox with the carb. will that work?

[curryd]

Thanks for the info.

I have a 04 450r with a JE Piston 11:1, Hot Cam Stage 2 cam, open airbox lid. What carb should I buy to get for it. Stock airbox. Do I have to buy different boots or with the stock ones work with the FCR carb. Also, what kind of jetting should I run, I live in Michigan.